This invention relates to a fluorescent display device, and more particularly to a fluorescent display device including a field emission cathode acting as an electron source.
A fluorescent display device is generally classified into two types depending on an electron source thereof. One is a filamentary cathode type fluorescent display device and the other is a field emission cathode (hereinafter referred also to "FEC") type fluorescent display device.
The fluorescent display device is generally constructed in such a manner that filamentary cathodes acting as an electron source, control electrodes and phosphor-deposited anodes functioning as a display section are housed or received in an envelope which is evacuated to a high vacuum.
The FEC type fluorescent display device uses a field emission cathode as its electron source and is generally used for a graphic display, wherein cathodes of the FEC and its gates cooperate to each other to form an X-Y matrix to directly control discharge of electrons from the cathodes and its anodes are formed into a solid shape, resulting in a graphic display desired being carried out.
Unfortunately, the conventional filamentary cathode type fluorescent display device requires a fitment for stretchedly arranging the filamentary cathodes, to thereby cause ends of the device to be cooled. This results in an area of the device which is capable of carrying out a display being significantly reduced, to thereby deteriorate a space factor. Also, the filamentary cathode type fluorescent display device causes a large amount of heat to be generated during the operation and therefore power consumption to be substantially increased. Further, it renders arrangement of spacers in the envelope highly difficult, leading to an increase in thickness and weight of the device.
The conventional FEC type fluorescent display device is directed to a graphic display, therefore, it is so constructed that a relatively high voltage is applied to the anode, to thereby drive the FEC at a reduced duty ratio, resulting in exhibiting luminance required. Unfortunately, such construction causes an increase in driving cost of the device and an excessive increase in voltage, so that the device is not suitable for use for a display of a low capacity other than a graphic display.